Body Sensations – Gin McCollum

BODY SENSATIONS: NEUROBIOLOGY, LEARNING TO FEEL, AND SENSORY TEAMWORK

BY GIN MCCOLLUM

Most of us must learn to feel, as an artist learns to see in order to draw. All of the physiological processes

of feeling and seeing can happen with no awareness at all, when the mind is wandering elsewhere. Essential

to the learning process is awareness, prajna. With no awareness, we have unconscious sensations, not

conscious perceptions.

The light striking the retina of the eye is the first step in seeing. A great deal more happens in the visual part of the cerebral cortex, at the back of the head, and along the pathways to it. The conscious experience of seeing is typically correlated with neural soles of the feet in Tadasana and the skin under the sit bones in Bhujapidasana, where they are draped over the arms, and the

activity in the visual part of the cerebral cortex. Probably the whole brain is reorganized in the process of becoming an artist.

Similarly, body feeling, or somatosensation, starts in receptors in the skin, muscles, tendons, ligaments, and joints. Pathways through the spinal cord to the brain communicate sensations. At the same time, the neural activity is combined, as light sensations are combined into lines and shapes before we see a scene. The process of learning to feel brings awareness, prajna, to these combinations of body sensations and to the whole experience of feeling.

We each learn individually how an asana feels. For example, in Tadasana, I feel the pressure on the soles of my feet, the muscle feel of straightening the hips and lifting the chest, and the skin stretch in the arms and hands. What do you feel? To stand upright, we also use vision, aligning ourselves to the trees or walls around us. The receptors of the inner ear communicate further gravitational information along pathways to the eyes, neck, and spinal cord. all the way from the back foot along my side to the fingertips of

Practicing the various asanas provides a framework for learning to feel, as drawing provides a framework for learning to see. An asana is typically experienced as a whole, rather than as a scattering of sensations. That whole experience is formed as the body sensations are combined in spinal pathways, the brainstem, and the brain. We will start with the receptors in the skin, familiar as touch, because their separate qualities tend to be easier to perceive.

Touch and the Various Receptors in the Skin tiny curlicues found in embroidery and filigree but placed separately. And they are much tinier. For example, the ball of each thumb contains about 500 touch receptors. Furthermore, there are different kinds of receptors for different sensations, such as light touch, deep pressure, motion of a hair, pain, and temperature. Of the many types of touch receptors and sensations, body position and movement are sensed particularly with deep pressure, skin stretch, and light touch.

Deep pressure is typically felt at the base of a pose, where the body rests against the ground. Such foundations include the Dandasana, along with the skin under the thighs and calves. Deep pressure is also felt in the forearms in Sirsasana. In addition to the deep pressure at the base of the pose, deep pressure may be felt where two body parts press against each other. For example, in Marichyasana III, the back of the upper arm presses against the outer knee, with both experiencing deep pressure. In Bakasana, the inner knees press into the upper arms. The inner knees also press into the upper arms in deep pressure between the limbs serves as a guide for staying in position and avoiding slipping.

Practicing the various asanas provides a framework for learning to feel, as drawing provides a framework for learning to see.

Skin stretch may be more individual. I feel skin stretch in my upper arms in Urdhva Hastasana in Tadasana. In Utthita Hasta Padangusthasana I, I feel skin stretch at the back of my lifted thigh. In Utthita Trikonasana, I feel skin stretch over the upper hip. Basically, skin stretch is felt where the asana asks us to elongate more than we usually do. As with deep pressure, skin stretch is often a good guide to the integrity of the pose. For example, in Utthita Parsvakonasana, am I really stretching well, The menagerie of touch receptors in the skin remind me of the

my up arm? Skin stretch can answer that question.

Light touch is often felt during movement. For example, your t-shirt may brush lightly against your skin as you move into a pose. Similarly, your hair may lightly brush your skin. The hair itself has its own receptors, spiraling around the hair follicle, giving hair a wonderful sensitivity to touch. A breeze may stir

Becoming aware of the separate sensations is one way to deepen the experiences of an asana and of movement.

your hair or lightly touch your skin. These light-touch receptors contribute almost all the time to the sensation of motion, as do the deep pressure and skin stretch receptors. T-shirt motion often forms part of the mix when performing simple trunk twists, such as are used to get into any number of asanas, for instance, Parsva Upavista Konasana. I notice light touch especially when I am practicing at home in loose, fleece pants, doing standing poses or inversions.

Becoming aware of the separate sensations is one way to deepen the experiences of an asana and of movement. However, body feelings are typically mixed. Awareness typically focuses on the feeling of a coherent body position or movement, not of a scattering of separate touch sensations.

The sensations most characteristic of the touch receptors of the skin are known because it has been convenient to do experiments in which special probes, such as fine hairs, are used to stimulate receptors separately. In addition, it has been possible to follow the way neural activity from receptors in the skin is combined as it follows pathways to the brain. Sensations on the fingertips and face are finely separable in awareness, whereas those on the back are only coarsely so. When sensations from a large area have been combined, especially from places that are more obscure, the brain sometimes assigns awareness to a different part of the area than the part that was stimulated. For example, stomach discomfort may be felt in the shoulders. Similarly, rotator cuff inflammation is often felt halfway down the upper arm. Such examples are called “referred pain.”

It has been more difficult to experimentally separate out the sensations from muscle, tendon, ligament, and joint receptors. This difficulty arises partly from the way the nervous system mixes the various sensations as they follow pathways to the brain. Awareness is thought to happen in the brain but can be of anything the nervous system contacts. In those pathways and in the brain, sensations become part of the team that shape a movement, such as walking or bringing a cup to your lips.

Muscle, Tendon, Ligament, and Joint Receptors In my current stage in Virabhadrasana III, I move slowly into the pose, keeping my body well balanced over the standing foot. In holding the pose, I take pleasure in the feeling of activating the muscles of the upper back and of the lifted leg, especially the back of the thigh. The balance issues make me aware of the small shifts in activity among the hip muscles of the standing leg. All of these muscle sensations use the muscle spindles, which wrap around muscle fibers somewhat the way hair follicle receptors wrap around hair follicles. About the hip, sensation is primarily by means of muscle receptors. However, more generally, position and movement are sensed by a combination of tendon, ligament, joint, and muscle receptors.

Muscle spindles include a special system that allows them to be particularly adaptable, as we change position or, perhaps, over time as our body changes with practice. A muscle spindle sits in the muscle tissue and feels it lengthen. Within the muscle spindle are separate little muscle fibers that keep the muscle spindle taut when the muscle contracts. The sensitivity of the muscle spindle and the little muscle fibers within the spindle cooperate to produce sensations appropriate to the movement. That cooperation gives the muscle spindle system extra adaptability, as we practice and learn to feel.

Standing poses such as Virabhadrasana III and Utthita Trikonasana challenge us to gain awareness of the muscle sensations associated with hip movements. Most people come to yoga with an ability to stand upright or align themselves visually with the walls, or both at once. However, sensitivity to hip movement and position is less common. Therefore, in learning Utthita Trikonasana, we are taught to visually align our feet to the walls and our trunks over the line between our feet. Vision tutors body feeling. Gradually, with the help of vision, we learn the sensations in our hips associated with rotating the front leg, with rotating the trunk over the front leg, and with turning the trunk up so that the top arm can reach straight up. These hip sensations are likely to be individual, because of the complexity of the hip musculature, shape and proportion differences between people, and differences in flexibility, which change with time and practice.

Awareness of the Whole Motion For movement, it is more important where you are reaching your arm or leg—in which direction and how far—rather than at what angle you are holding your knee or elbow. For example, coming down out of Ardha Chandrasana, the top foot reaches for the floor at a suitable distance behind the standing foot. You can’t see, but everyday practice has given you the body feeling to place that foot. Everyday movements include reaching a foot toward a step or a hand toward a pencil, so that unfolding an arm or leg to the right combination of hip-knee-ankle or shoulder-elbow-wrist angles is well-practiced.

One of the early tasks in asana practice is to jump or step the feet four to four and a half feet apart for standing poses. At first, we peer at our feet, visually estimating the distance between. With practice, body feeling can take over in sensing a wide, wider, or very wide stance. A person could probably become quite accurate at jumping the feet to a particular distance with the eyes closed. However, it’s natural to continue using cooperation between vision and body feeling. Teamwork among senses is the norm in movement, where the cooperation